This invention relates to the art of land vehicles and, more particularly, to controlling air flow between portions of truck type wheeled vehicles to reduce turbulence and air drag thereon during movement along a roadway.
The present invention find particular utility in connection with truck type vehicles generally called tractor-trailer units in which the tractor is the draft vehicle and the trailer has an articulated connection therwith and is towed thereby as the trailing vehicle. Accordingly, the invention is disclosed and described herein in conjunction with such a draft and trailing vehicle combination. At the same time, it will be appreciated that the invention is applicable to truck type vehicles other than articulated draft and trailing vehicle combinations such as, for example, a unitary truck structure having a power plant and cab on the front portion of the truck frame and a storage compartment on the rear portion of the frame and having a front wall at or spaced behind the rear wall of the cab and projecting laterally outwardly and/or vertically above the side and top walls of the cab.
It is of course well known in connection with the towing of a trailing vehicle along a roadway that considerable energy in the form of fuel consumption is required to overcome air resistance and air drag on the trailing vehicle. In this respect, with regard for example to the common tractor-trailer combination, the trailer includes a wall at the front end thereof spaced behind the cab of the tractor, whereby air flowing rearwardly along the tractor in response to movement of the tractor-trailer along a roadway enters the space therebetween and creates a vortex effect or air turbulence in the space. Moreover, air flowing across the space impinges directly against portions of the front wall of the trailer which extend vertically above and/or laterally outwardly of the top and side walls of the cab of the tractor. Still further, air flowing laterally upward and outwardly along the front wall of the trailer and around the top and side edges thereof causes additional vortex effects and thus air drag along the top and side walls of the trailer rearwardly of the edges of the front wall.
Such air resistance and air drag, of course, imposes a corresponding load on the power plant of a tractor towing a trailer at a given velocity relative to ground. Moreover, if the tractor-trailer is moving against a head wind, the relative velocity of air causing such resistance and drag forces is increased above the velocity of the tractor relative to ground by the velocity of such a head wind, thus further increasing the load on the power plant of the tractor. The load on the power plant of a tractor of course translates to fuel consumption and, with respect to a given tractor-trailer combination, an undesirably high fuel consumption is required to overcome such resistance and drag forces in order to maintain a desired velocity of the vehicles relative to ground.